As an airbag for vehicles, there is an airbag for lateral collision adapted, upon a lateral collision of a vehicle, to spread forwards from a side of the backrest to protect a passenger. (A similar art is disclosed in Japanese Patent Application Laid-Open Publication No. 9-136598.)
When spread, such a type of airbag has a generally L-shape external configuration partitioned by an internal partition cloth into a head protecting upper portion and a chest protecting lower portion. The airbag has a proximal end provided with an inflator. Discharged gas from a discharge port at a side of the inflator first enters the chest protecting portion, spreading this forwards, and then rushes through a communication hole across the partition cloth inside the head protecting portion, spreading this upwards.
Such an airbag for lateral collision needs to have a chest protecting portion quickly spread into a relatively narrow spacing between a passenger and a side wall of a vehicle body, as well as an implementation to avoid, when spreading, interferences such as with the vehicle body's side wall, for example.
The action and speed of the spreading of an airbag depends on how the airbag is folded.
To this point, it is desirable to propose a folding structure and a folding method for an airbag, allowing an improved spreading speed, as well as for the action of spread to be smooth without failure due to an interference with a vehicle body side wall.